1. Field of the Invention
The present invention relates to an optical device such a television lens capable of controlling a lens iris, an extender etc. by an electrical signal from a television camera and returning the lens status by an electrical signal to the camera.
2. Related Background Art
The television lens for broadcasting is capable of controlling lens operations such as iris, extender, tally etc. by electrical signals from the television camera, and returning the lens status such as positions of extender, iris, zooming and focusing to the television camera by electrical signals.
The exchange of such signals is executed by a connector provided at the junction between the camera and the lens, but the kind of the connector, the pin assignment to the signals and the signal level depend of the manufacturer of the television camera.
Also the mechanical configuration of the joint (hereinafter called mount) between the television camera and the lens depends of the manufacturer of the television cameras. FIGS. 6 and 7 show different mount shapes adopted by different manufacturers A and B. For this reason, even a same lens is slightly modified for the respective television camera manufacturer.
To deal with such situation, in the lens unit, each manufacturers preparates a mount for mechanically adapting to different television cameras and provides a variation of set, adjustment, or replacement of the board in the lens for electrically adapting to different television cameras.
Thus, a lens of a same optical performance can be adapted to the different mechanical configurations and the different electrical interfaces of the cameras, with the minimum replacement of parts.
FIG. 5 shows a conventional lens system.
Electrical signals from a camera 8 are directly input to a main process circuit board (PCB) 43 of a lens 41, through bidirectional connectors 7 and a mount 44 of the television lens and the television camera. The PCB 43 executes various operations such as auto focusing and auto iris control.
The mount 44 of the lens 41 is also provided with an auxiliary switch 45 and an indicator 46, which are directly connected also to the PCB 43.
For matching with the electrical interface adopted by each camera manufacturer, there are executed exclusive wiring and resetting of the main PCB 43, or replacement to an exclusive circuit board and exclusive adjustment for the camera manufacturer.
In such method, however, the electrical interface has to be matched with each camera manufacturer, so that the electrical adjusting and setting methods can only be determined when the camera is determined. Consequently there are required various adjusting methods, leading to complicated electrical adjustment.
In case the lens is delivered to a rental company, such lens has to be mounted on the cameras of various manufacturers, so that the replacement of the above-mentioned mount and electrical interface is often executed by the user (rental company) who is sometimes required to execute complex electrical adjustments.